The disclosure relates to an exhaust gas sensor capable of sensing at least oxygen and oxides of nitrogen (NOx) content.
Exhaust gas generated by combustion of fossil fuels in furnaces, ovens, and engines contain, for example, NOx, unburned hydrocarbons (HC), and carbon monoxide (CO). Vehicles, e.g., diesel vehicles, utilize various pollution-control after treatment systems, such as a NOx absorber(s) and/or selective catalytic reduction (SCR) catalyst(s), to reduce NOx. Thus, NOx sensors are becoming more prevalent in vehicles, particularly diesel vehicles.
Current NOx sensors on the market use oxygen pump cell technology that is expensive and complicated to produce. There also are some performance limitations to current NOx sensors, such as cross-interference from other gases and accuracy that is not in line with customer expectations.
Commercial NOx sensors are built with two or three in-cascade electrochemical pumping cells requiring eight lead wires for sensor control and operation. In addition to being complicated and cost ineffective, the sensor can only output oxygen concentration and total NOx concentration in ppm. Trying to combine more sensing features into the device (such as ammonia (NH3), nitrogen monoxide (NO), nitrogen dioxide (NO2) sensing) would require more than eight lead wires, adding even more complexity and difficulty to its packaging and manufacture.
What is needed is a combined oxygen and NOx sensor that is accurate, simpler to manufacture, and more cost effective.